Failure to ferment dietary resistant starch in specific mouse models of obesity results in no body fat loss

Effects of resistant starch on anti-obesity status and nutrient digestibility in dogs

This study investigated the effects of corn resistant starch (RS) on the anti-obesity properties, nutrient digestibility, and blood parameters in healthy beagles. Four spayed and six castrated beagle dogs were divided into a control group (CON) with a diet comprising rice and chicken meal and a treatment group (TRT) with a diet comprising corn with an increased RS content by heating-cooling and chicken meal. All dogs in the CON and TRT groups were fed a 1.2-fold higher energy diet than the daily recommended energy requirement for 16 weeks. Throughout the study period, the body weight of dogs in CON increased, whereas no change in body weight was observed in TRT, resulting in a significant difference in body weight between the two groups at the end of the experiment. Moreover, a significant reduction in the apparent total tract digestibility was observed upon the analysis of dry matter, nitrogen-free extract, and organic matter in TRT compared with that in CON. The complete blood cell composition and biochemical parameters were within the reference range in both groups. A significant increase in the concentration of serum adiponectin was found in TRT at the end of the experiment. These results suggest that the corn RS may be beneficial for weight management owing to its reduced nutrient digestibility.

Gut Microbiota Composition and Predicted Microbial Metabolic Pathways of Obesity Prone and Obesity Resistant Outbred Sprague-Dawley CD Rats May Account for Differences in Their Phenotype

Like humans, outbred Sprague-Dawley CD rats exhibit a polygenic pattern of inheritance of the obese phenotype and not all individuals exposed to a high calorie intake develop obesity. We hypothesized that differences in gut microbiota composition account for phenotype differences between obese prone (OP) and obese resistant (OR) rats. We studied the gut microbiota composition of OPand OR rats after a high fat (HF) diet and how they respond to fermentation of resistant starch (RS). In phase 1 of the study 28 OP and 28 OR rats were fed a HF diet. In order to determine causal role of microbiota on phenotypes, In phase 2, a microbiota transplant between the two phenotypes was performed before switching all rats to a HF diet supplemented with 20% RS. We determined microbiota composition by 16S sequencing and predicted microbiota function by PICRUSt2. Despite a similar calorie intake, in phase 2 OP rats gained more weight and accumulated more abdominal fat in both phase 1 and 2 compared to OR rats (P < 0.001; n = 6). The OP rats fermented RS more robustly compared with OR rats with an increase in total bacteria, short chain fatty acids, and increased weight of the cecum, but microbiota of OP rats had much lower alpha diversity and evenness. The microbiota of OP rats, had higher amounts of bacteria from order Bacteroidales, specifically family Muribaculaceae (S24-7), which is known to possess several starch degrading enzymes and was reported in previous studies to increase with fermentation of RS. The OR rats fermented RS less but had higher bacterial diversity and evenness and had significantly higher bacterial counts from phylum Firmicutes particularly order Clostridiales, genus Clostridium and an uncultured bacterium of the genus Akkermansia. The microbiota of OR rats had enhanced bacterial chemotaxis, phosphotransferase system (PTS), and fatty acid biosynthesis compared to OP rats whose microbiota had higher glycan degradation and LPS biosynthesis pathways. The microbiota transplant did not change obesity phenotype or microbiota composition. In conclusion, a higher alpha-diversity and evenness of the microbiota and higher proportions of Clostridiales and Akkermansia in OR rats were associated with a better metabolic phenotype with lower body fat. However, robust RS fermentation caused a lower diversity and evenness and did not result in a leaner phenotype.

Butyrate: A Review on Beneficial Pharmacological and Therapeutic Effect

Background::

Short-chain fatty acids (SCFAs), generally acetate, propionate along with butyrate, are aliphatic organic acids formed in the gut mucosa through bacterial fermentation of mostly undigested nutritional carbohydrates, again to a minor degree by natural and dietary proteins, such as mucous and shed epithelial cells.

Methods::

Many sources were used to collect information about Butyrate, such as Pub med, Google Scholar, Pubmed, Scopus and other reliable sources.

:

Endogenous butyrate formation, absorption, and transportation by colon cells have now been well acknowledged. Butyrate exerts its action features by way of appearing as a histone deacetylase inhibitor, even signaling through a few protein receptors. Lately, butyrate has received special consideration for its favorable result on intestinal equilibrium and also energy metabolism. There is a growing interest in butyrate as its impact on epigenetic mechanisms will result in much more certain and also efficacious healing techniques for the prevention and therapy of various diseases that range from genetic conditions to other body disorders.

Conclusion::

With this assessment, we compile the existing information on the attributes of butyrate, particularly its potential effects and also mechanisms involved in cancer, inflammation, diabetes mellitus, neurological and cardiovascular disorder.

Differences in Capacity of High-Amylose Resistant Starch, Whole-Grain Flour, and a Combination of Both to Modify Intestinal Responses of Male Sprague Dawley Rats Fed Moderate and High Fat Diets

Gastrointestinal tract (GIT) responses to a high-amylose resistant starch (RS) product were compared to those observed when RS was combined with whole grain (WG) and to controls with low RS intake in rats fed moderate or high fat diets. Regardless of fat intake, rats fed RS or WG + RS diets had higher cecum weights, higher intestinal quantities of short chain fatty acids, and lower intestinal content pH, and their GIT cells had increased gene expression for gluconeogenesis and barrier function compared to controls. Whereas RS resulted in greater GIT content acetate and propionate and lowest pH, the WG + RS diets yielded higher butyrate. Rats fed the RS diet with MF had higher cecum weights than those fed either the RS diet with HF or the WG + RS diet with either MF or HF. Diets containing combinations of RS and other dietary fibers should be considered for RS-mediated GIT benefits.

Dietary type 2 resistant starch improves systemic inflammation and intestinal permeability by modulating microbiota and metabolites in aged mice on high-fat diet

Type 2 resistant starch (RS2) is a fermentable dietary fiber conferring health benefits. We investigated the effects of RS2 on host, gut microbiota, and metabolites in aged mice on high-fat diet. In eighteen-month old mice randomly assigned to control, high-fat (HF), or high-fat+20% RS2 (HFRS) diet for 16 weeks, RS2 reversed the weight gain and hepatic steatosis induced by high-fat diet. Serum and fecal LPS, colonic IL-2 and hepatic IL-4 mRNA expressions decreased while colonic mucin 2 mRNA and protein expressions increased in the HFRS compared to the HF and the control group. 16s rRNA sequencing of fecal microbial DNA demonstrated that RS2 decreased the abundance of pathogen taxa associated with obesity, inflammation, and aging including Desulfovibrio (Proteobacteria phylum), Ruminiclostridium 9, Lachnoclostridium, Helicobacteria, Oscillibacter, Alistipes, Peptococcus, and Rikenella. Additionally, RS2 increased the colonic butyric acid by 2.6-fold while decreasing the isobutyric and isovaleric acid levels by half compared to the HF group. Functional analyses based on Clusters of Orthologous Groups showed that RS2 increased carbohydrate while decreasing amino acid metabolism. These findings demonstrate that RS2 can reverse weight gain, hepatic steatosis, inflammation, and increased intestinal permeability in aged mice on high-fat diet mediated by changes in gut microbiome and metabolites.

A Lowly Digestible-Starch Diet after Weaning Enhances Exogenous Glucose Oxidation Rate in Female, but Not in Male, Mice

Starches of low digestibility are associated with improved glucose metabolism. We hypothesise that a lowly digestible-starch diet (LDD) versus a highly digestible-starch diet (HDD) improves the capacity to oxidise starch, and that this is sex-dependent. Mice were fed a LDD or a HDD for 3 weeks directly after weaning. Body weight (BW), body composition (BC), and digestible energy intake (dEI) were determined weekly. At the end of the intervention period, whole-body energy expenditure (EE), respiratory exchange ratio (RER), hydrogen production, and the oxidation of an oral ¹³C-labelled starch bolus were measured by extended indirect calorimetry. Pancreatic amylase activity and total ¹³C hepatic enrichment were determined in females immediately before and 4 h after administration of the starch bolus. For both sexes, BW, BC, and basal EE and RER were not affected by the type of starch, but dEI and hydrogen production were increased by the LDD. Only in females, total carbohydrate oxidation and starch-derived glucose oxidation in response to the starch bolus were higher in LDD versus HDD mice; this was not accompanied by differences in amylase activity or hepatic partitioning of the ¹³C label. These results show that starch digestibility impacts glucose metabolism differently in females versus males.

Metabolic Effects of Resistant Starch Type 2: A Systematic Literature Review and Meta-Analysis of Randomized Controlled Trials

Published evidence exploring the effects of dietary resistant starch (RS) on human cardiometabolic health is inconsistent. This review aimed to investigate the effect of dietary RS type 2 (RS2) supplementation on body weight, satiety ratings, fasting plasma glucose, glycated hemoglobin (HbA1c), insulin resistance and lipid levels in healthy individuals and those with overweight/obesity, the metabolic syndrome (MetS), prediabetes or type 2 diabetes mellitus (T2DM). Five electronic databases were searched for randomized controlled trials (RCTs) published in English between 1982 and 2018, with trials eligible for inclusion if they reported RCTs involving humans where at least one group consumed ≥ 8 g of RS2 per day and measured body weight, satiety, glucose and/or lipid metabolic outcomes. Twenty-two RCTs involving 670 participants were included. Meta-analyses indicated that RS2 supplementation significantly reduced serum triacylglycerol concentrations (mean difference (MD) = -0.10 mmol/L; 95% CI -0.19, -0.01, P = 0.03) in healthy individuals (n = 269) and reduced body weight (MD = -1.29 kg; 95% CI -2.40, -0.17, P = 0.02) in people with T2DM (n = 90). However, these outcomes were heavily influenced by positive results from a small number of individual studies which contradicted the conclusions of the majority of trials. RS2 had no effects on any other metabolic outcomes. All studies ranged from 1-12 weeks in duration and contained small sample sizes (10-60 participants), and most had an unclear risk of bias. Short-term RS2 supplementation in humans is of limited cardiometabolic benefit.

Inulin fiber dose-dependently modulates energy balance, glucose tolerance, gut microbiota, hormones and diet preference in high-fat-fed male rats

Inulin, a popular prebiotic fiber, has been reported to promote satiety and fat loss; however, the dose-response effects of inulin on energy balance and diet preference, and whether the metabolic effects are independent of calorie restriction are not well characterized. Therefore, we compared the effects of diets varying in inulin concentrations on food intake, energy expenditure, body composition, gut microbiota and hormones, and assessed whether inulin-induced hypophagia was due to reduced diet preference. In experiment 1, male rats were randomized to six high-fat diet groups: control (CON, 0% inulin), 2.5% inulin (2.5IN), 10% inulin (10IN), 25% inulin (25IN), 25% cellulose (25CE) or pair-fed to 25IN (25PF) for 21 days. We demonstrate that inulin dose-dependently decreased caloric intake and respiratory quotient; improved glucose tolerance; increased the abundance of Bacteroidetes and Bifidobacterium spp.; decreased Clostridium clusters I and IV; increased butyryl-CoA:acetate CoA-transferase in cecum; upregulated peptide YY, cholecystokinin and proglucagon transcripts in the cecum and colon; and increased plasma peptide YY and glucagon-like peptide-1 concentrations. Importantly, unlike 25PF, 25IN attenuated the reduction in energy expenditure associated with calorie restriction and decreased adiposity. In experiment 2, following four training periods, diet preferences were determined. Although 10IN and 25IN decreased caloric intake, and 25CE increased caloric intake, during training, all high-fiber diets were less preferred. Taken together, this work demonstrates that inulin dose-dependently decreased caloric intake, modulated gut microbiota and upregulated satiety hormones, with metabolic effects being largely independent of caloric restriction.

CD Obesity-Prone Rats, but not Obesity-Resistant Rats, Robustly Ferment Resistant Starch Without Increased Weight or Fat Accretion

OBJECTIVE

This study used CD obesity-prone (OP) and obesity-resistant (OR) rats to examine how weight gain and fat accretion relate to fermentation levels and microbiota composition after feeding resistant starch (RS).

METHODS

After feeding OP rats and OR rats a high-fat (HF) diet for 4 weeks, rats were stratified into three groups: they were fed either an HF diet (group 1: HF-HF) or were switched to a low-fat (LF) diet (group 2: HF-LF) or an LF diet supplemented with 20% RS by weight for 4 weeks (group 3: HF-LFRS). Energy intake, body weight, fermentation variables, and microbiota composition were determined.

RESULTS

In OP rats, RS elicited robust fermentation (increased cecal contents, short-chain fatty acids, and serum glucagon-like peptide 1). Total bacteria, species of the Bacteroidales family S24-7, and the archaean Methanobrevibacter smithii increased. The robust fermentation did not elicit higher weight or fat accretion when compared with that of control rats fed the same isocaloric diets (HF-LF ± RS). In OR rats, body weight and fat accretion were also not different between HF-LF ± RS diets, but RS elicited minimal changes in fermentation and microbiota composition.

CONCLUSIONS

Robust fermentation did not contribute to greater weight. Fermentation levels and changes in microbiota composition in response to dietary RS differed by obesity phenotype.

Role of resistant starch on diabetes risk factors in people with prediabetes: Design, conduct, and baseline results of the STARCH trial

Dietary resistant starch (RS) might alter gastrointestinal tract function in a manner that improves human health, particularly among adults at risk for diabetes. Here, we report the design and baseline results (with emphasis on race differences) from the STARCH trial, the first comprehensive metabolic phenotyping of people with prediabetes enrolled in a randomized clinical trial testing the effect of RS on risk factors for diabetes. Overweight/obese participants (BMI≥27kg/m2 and weight≤143kg), age 35-75y, with confirmed prediabetes were eligible. Participants were randomized to consume 45g/day of RS (RS=amylose) or amylopectin (Control) for 12weeks. The study was designed to evaluate the effect of RS on insulin sensitivity and secretion, ectopic fat, and inflammatory markers. Secondary outcomes included energy expenditure, substrate oxidation, appetite, food intake, colonic microbial composition, fecal and plasma levels of short-chain fatty acids, fecal RS excretion, and gut permeability. Out of 280 individuals screened, 68 were randomized, 65 started the intervention, and 63 were analyzed at baseline (mean age 55y, BMI 35.6kg/m2); 2 were excluded from baseline analyses due to abnormal insulin and diabetes. Sex and race comparisons at baseline were reported. African-Americans had higher baseline acute insulin response to glucose (AIRg measured by frequently sampled intravenous glucose tolerance test) compared to Caucasians, despite having less visceral adipose tissue mass and intrahepatic lipid; all other glycemic variables were similar between races. Sleep energy expenditure was ~90-100kcal/day lower in African-Americans after adjusting for insulin sensitivity and secretion. This manuscript provides an overview of the strategy used to enroll people with prediabetes into the STARCH trial and describes methodologies used in the assessment of risk factors for diabetes. Clinicaltrials.gov identifier: STARCH (NCT01708694). The present study reference can be found here: https://clinicaltrials.gov/ct2/show/NCT01708694. Submission Category: "Study Design, Statistical Design, Study Protocols".

Dietary resistant starch type 4-derived butyrate attenuates nuclear factor-kappa-B1 through modulation of histone H3 trimethylation at lysine 27

Indigestible resistant starches (RS) are substrates for gut-microbial metabolism and have been shown to attenuate intestinal inflammation but the supporting evidence is inconsistent and lacks mechanistic explanation. We have recently reported dietary RS type 4 (RS4) induced improvements in immunometabolic functions in humans and a concomitant increase in butyrogenic gut-bacteria. Since inflammation is a key component in metabolic diseases, here we investigated the effects of RS4-derived butyrate on the epigenetic repression of pro-inflammatory genes in vivo and in vitro. RS4-fed mice, compared to the control-diet group, had higher cecal butyrate and increased tri-methylation of lysine 27 on histone 3 (H3K27me3) in the promoter of nuclear factor-kappa-B1 (NFκB1) in the colon tissue. The H3K27me3-enrichment inversely correlated with the concentration dependent down-regulation of NFκB1 in sodium butyrate treated human colon epithelial cells. Two additional inflammatory genes were attenuated by sodium butyrate, but were not linked with H3K27me3 changes. This exploratory study presents a new opportunity for studying underlying H3K27me3 and other methylation modifying mechanisms linked to RS4 biological activity.

Short Chain Fatty Acids in the Colon and Peripheral Tissues: A Focus on Butyrate, Colon Cancer, Obesity and Insulin Resistance

Increased dietary fiber consumption has been associated with many beneficial effects, including amelioration of obesity and insulin resistance. These effects may be due to the increased production of short chain fatty acids, including propionate, acetate and butyrate, during fermentation of the dietary fiber in the colon. Indeed, oral and dietary supplementation of butyrate alone has been shown to prevent high fat-diet induced obesity and insulin resistance. This review focuses on sources of short chain fatty acids, with emphasis on sources of butyrate, mechanisms of fiber and butyrate metabolism in the gut and its protective effects on colon cancer and the peripheral effects of butyrate supplementation in peripheral tissues in the prevention and reversal of obesity and insulin resistance.

Spent turmeric reduces fat mass in rats fed a high-fat diet

Indigestible carbohydrates may improve obesity. Spent turmeric contains high levels of dietary fibre and resistant starch (RS), which have fermentation potential in vitro. We hypothesised that indigestible carbohydrates in spent turmeric might prevent obesity development. In the first study, rats were administered 10% turmeric powder (TP) or spent turmeric powder (STP) in a high-fat (HF) diet for 28 d. In the second study, rats were fed 10% STP in a HF diet with or without antibiotics for 15 d. In the third study, rats were treated with a STP-containing suspension. In study 1, the TP and STP diet increased the caecal short-chain fatty acid (SCFA) content compared to that of a control diet. The lower energy intake in the TP and STP group was strongly related to the decrease in visceral fat weight. In study 2, after caecal fermentation suppression with antibiotics, STP treatment decreased the visceral fat mass. In study 3, the plasma glucose levels and incremental area under the curve (AUC) after ingestion of a STP-containing suspension were lower than those after ingestion of suspension alone. These findings suggest the reduction of carbohydrate absorption during the gastrointestinal passage after TP and STP treatment. Our data indicate that the reduced obesity development in rats fed a HF diet may be attributed to the low metabolisable energy density of carbohydrates in the spent turmeric, independent of SCFA-mediated factors.

Obese ZDF rats fermented resistant starch with effects on gut microbiota but no reduction in abdominal fat

SCOPE

To determine if whole-grain (WG) flour with resistant starch (RS) will produce greater fermentation than isolated RS in obese Zucker Diabetic Fatty (ZDF) rats, and whether greater fermentation results in different microbiota, reduced abdominal fat, and increased insulin sensitivity.

METHODS AND RESULTS

This study utilized four groups fed diets made with either isolated digestible control starch, WG control flour (6.9% RS), isolated RS-rich corn starch (25% RS), or WG corn flour (25% RS). ZDF rats fermented RS and RS-rich WG flour to greatest extent among groups. High-RS groups had increased serum glucagon-like peptide 1 (GLP-1) active. Feeding isolated RS showed greater Bacteroidetes to Firmicutes phyla among groups, and rats consuming low RS diets possessed more bacteria in Lactobacillus genus. However, no differences in abdominal fat were observed, but rats with isolated RS had greatest insulin sensitivity among groups.

CONCLUSIONS

Data demonstrated ZDF rats (i) possess a microbiota that fermented RS, and (ii) WG high-RS fermented better than purified RS. However, fermentation and microbiota changes did not translate into reduced abdominal fat. The defective leptin receptor may limit ZDF rats from responding to increased GLP-1 and different microbiota for reducing abdominal fat, but did not prevent improved insulin sensitivity.

Disparate Metabolic Responses in Mice Fed a High-Fat Diet Supplemented with Maize-Derived Non-Digestible Feruloylated Oligo- and Polysaccharides Are Linked to Changes in the Gut Microbiota

Studies have suggested links between colonic fermentation of dietary fibers and improved metabolic health. The objectives of this study were to determine if non-digestible feruloylated oligo- and polysaccharides (FOPS), a maize-derived dietary fiber, could counteract the deleterious effects of high-fat (HF) feeding in mice and explore if metabolic benefits were linked to the gut microbiota. C57BL/6J mice (n = 8/group) were fed a low-fat (LF; 10 kcal% fat), HF (62 kcal% fat), or HF diet supplemented with FOPS (5%, w/w). Pronounced differences in FOPS responsiveness were observed: four mice experienced cecal enlargement and enhanced short chain fatty acid production, indicating increased cecal fermentation (F-FOPS). Only these mice displayed improvements in glucose metabolism compared with HF-fed mice. Blooms in the gut microbial genera Blautia and Akkermansia were observed in three of the F-FOPS mice; these shifts were associated with reductions in body and adipose tissue weights compared with the HF-fed control mice. No improvements in metabolic markers or weights were detected in the four mice whose gut microbiota did not respond to FOPS. These findings demonstrate that FOPS-induced improvements in weight gain and metabolic health in mice depended on the ability of an individual's microbiota to ferment FOPS.

Improving healthspan via changes in gut microbiota and fermentation

Dietary resistant starch impact on intestinal microbiome and improving healthspan is the topic of this review. In the elderly population, dietary fiber intake is lower than recommended. Dietary resistant starch as a source of fiber produces a profound change in gut microbiota and fermentation in animal models of aging. Dietary resistant starch has the potential for improving healthspan in the elderly through multiple mechanisms as follows: (1) enhancing gut microbiota profile and production of short-chain fatty acids, (2) improving gut barrier function, (3) increasing gut peptides that are important in glucose homeostasis and lipid metabolism, and (4) mimicking many of the effects of caloric restriction including upregulation of genes involved in xenobiotic metabolism.

Role of Micro RNA-205 in Promoting Visceral Adiposity of NZ10 Mice with Polygenic Susceptibility for Type 2 Diabetes

SCOPE

To characterize diet-dependent miRNA profiles and their targets in the visceral adipose of mice with polygenic susceptibility to type 2 diabetes.

METHODS AND RESULTS

Six-week NONcNZO10/LtJ (NZ10) and control SWR/J mice were subjected to high protein-fish oil or control diets for 19 weeks and micro-RNA microarray analyses were implemented on visceral adipose RNA. We found that 27 miRNAs were significantly induced and 10 significantly repressed in the VA of obese NZ10 mice compared with controls. 12 selected regulated miRNAs were confirmed by RT-PCR based on the microarray data and we demonstrated that the expression of these miRNAs remained unaltered in the VA of control SWR mice. To assess the possible functional roles of miRNAs in adipogenesis, we also analyzed their expression in 3T3-L1 cells during growth and differentiation. This revealed that suppression of miRNA-205 alone correlated selectively with increased cell proliferation and lipid formation of adipocytes.

CONCLUSION

Diet and genetics control the expression of obesity-regulated miRNAs in the visceral adipose of NZ10 mice.

The importance of GLP-1 and PYY in resistant starch's effect on body fat in mice

Resistant starch (RS) is a dietary fermentable fiber that decreases body fat accumulation, and stimulates the secretion of glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) in rodents. GLP-1 and PYY are gut-secreted hormones with antiobesity effect. Thus, blocking the signals of increased GLP-1 and PYY may also block the effect of dietary RS on body fat. In a 10-week study, C57BL/6J and GLP-1 receptor null (GLP-1R KO) mice were fed control or 30% RS diet, and received daily intraperitoneal injection of either saline or PYY receptor antagonist (BIIE0246, 20 μg/kg body weight). Dietary RS significantly decreased body fat accumulation only in wild-type mice that has saline injection, but not in GLP-1R KO mice. PYY receptor antagonist diminished RS action on body fat in wild-type mice, but did not interfere with GLP-1R KO mice response to RS. Regardless of genotype and injection received, all RS-fed mice had increased cumulative food intake, cecal fermentation, and mRNA expression of proglucagon and PYY. Thus, our results suggest that increased GLP-1 and PYY is important in RS effects on body fat accumulation.

Role of resistant starch in improving gut health, adiposity, and insulin resistance

The realization that low-glycemic index diets were formulated using resistant starch led to more than a decade of research on the health effects of resistant starch. Determination of the metabolizable energy of the resistant starch product allowed for the performance of isocaloric studies. Fermentation of resistant starch in rodent studies results in what appears to be a healthier gut, demonstrated by increased amounts of short-chain fatty acids, an apparent positive change in the microbiota, and increased gene expression for gene products involved in normal healthy proliferation and apoptosis of potential cancer cells. Additionally, consumption of resistant starch was associated with reduced abdominal fat and improved insulin sensitivity. Increased serum glucagon-like peptide 1 (GLP-1) likely plays a role in promoting these health benefits. One rodent study that did not use isocaloric diets demonstrated that the use of resistant starch at 8% of the weight of the diet reduced body fat. This appears to be approximately equivalent to the human fiber requirement. In human subjects, insulin sensitivity is increased with the feeding of resistant starch. However, only 1 of several studies reports an increase in serum GLP-1 associated with resistant starch added to the diet. This means that other mechanisms, such as increased intestinal gluconeogenesis or increased adiponectin, may be involved in the promotion of improved insulin sensitivity. Future research may confirm that there will be improved health if human individuals consume the requirement for dietary fiber and a large amount of the fiber is fermentable.

Role of resistant starch in improving gut health, adiposity, and insulin resistance

The realization that low-glycemic index diets were formulated using resistant starch led to more than a decade of research on the health effects of resistant starch. Determination of the metabolizable energy of the resistant starch product allowed for the performance of isocaloric studies. Fermentation of resistant starch in rodent studies results in what appears to be a healthier gut, demonstrated by increased amounts of short-chain fatty acids, an apparent positive change in the microbiota, and increased gene expression for gene products involved in normal healthy proliferation and apoptosis of potential cancer cells. Additionally, consumption of resistant starch was associated with reduced abdominal fat and improved insulin sensitivity. Increased serum glucagon-like peptide 1 (GLP-1) likely plays a role in promoting these health benefits. One rodent study that did not use isocaloric diets demonstrated that the use of resistant starch at 8% of the weight of the diet reduced body fat. This appears to be approximately equivalent to the human fiber requirement. In human subjects, insulin sensitivity is increased with the feeding of resistant starch. However, only 1 of several studies reports an increase in serum GLP-1 associated with resistant starch added to the diet. This means that other mechanisms, such as increased intestinal gluconeogenesis or increased adiponectin, may be involved in the promotion of improved insulin sensitivity. Future research may confirm that there will be improved health if human individuals consume the requirement for dietary fiber and a large amount of the fiber is fermentable.

Starving our microbial self: the deleterious consequences of a diet deficient in microbiota-accessible carbohydrates

The gut microbiota of a healthy person may not be equivalent to a healthy microbiota. It is possible that the Western microbiota is actually dysbiotic and predisposes individuals to a variety of diseases. The asymmetric plasticity between the relatively stable human genome and the more malleable gut microbiome suggests that incompatibilities between the two could rapidly arise. The Western lifestyle, which includes a diet low in microbiota-accessible carbohydrates (MACs), has selected for a microbiota with altered membership and functionality compared to those of groups living traditional lifestyles. Interactions between resident microbes and host leading to immune dysregulation may explain several diseases that share inflammation as a common basis. The low-MAC Western diet results in poor production of gut microbiota-generated short-chain fatty acids (SCFAs), which attenuate inflammation through a variety of mechanisms in mouse models. Studies focused on modern and traditional societies, combined with animal models, are needed to characterize the connection between diet, microbiota composition, and function. Differentiating between an optimal microbiota, one that increases disease risk, and one that is causative or potentiates disease will be required to further understand both the etiology and possible treatments for health problems related to microbiota dysbiosis.

Thermal acclimation and nutritional history affect the oxidation of different classes of exogenous nutrients in Siberian hamsters, Phodopus sungorus

During acclimatization to winter, changes in morphology and physiology combined with changes in diet may affect how animals use the nutrients they ingest. To study (a) how thermal acclimation and (b) nutritional history affect the rates at which Siberian hamsters (Phodopus sungorus) oxidize different classes of dietary nutrients, we conducted two trials in which we fed hamsters one of three (13) C-labeled compounds, that is, glucose, leucine, or palmitic acid. We predicted that under acute cold stress (3 hr at 2°C) hamsters previously acclimated to cold temperatures (10°C) for 3 weeks would have higher resting metabolic rate (RMR) and would oxidize a greater proportion of dietary fatty acids than animals acclimated to 21°C. We also investigated how chronic nutritional stress affects how hamsters use dietary nutrients. To examine this, hamsters were fed four different diets (control, low protein, low lipid, and low-glycemic index) for 2 weeks. During cold challenges, hamsters previously acclimated to cold exhibited higher thermal conductance and RMR, and also oxidized more exogenous palmitic acid during the postprandial phase than animals acclimated to 21°C. In the nutritional stress trial, hamsters fed the low protein diet oxidized more exogenous glucose, but not more exogenous palmitic acid than the control group. The use of (13) C-labeled metabolic tracers combined with breath testing demonstrated that both thermal and nutritional history results in significant changes in the extent to which animals oxidize dietary nutrients during the postprandial period.

Resistant starch from high amylose maize (HAM-RS2) and dietary butyrate reduce abdominal fat by a different apparent mechanism

OBJECTIVE

Obesity is a health concern. Resistant starch (RS) type 2 from high-amylose maize (HAM-RS2) and dietary sodium butyrate (SB) reduce abdominal fat in rodents. RS treatment is associated with increased gut hormones peptide YY (PYY) and glucagon-like peptide 1 (GLP-1), but it is not known if SB increases these hormones.

DESIGN AND METHODS

This was investigated in a 2 × 2 rat study with HAM-RS2 (0 or 28% weight) and dietary sodium butyrate (0 and 3.2%) resulting in isocaloric treatments: energy control (EC), sodium butyrate (SB), HAM-RS2 (RS), and the combination (SBRS).

RESULTS

RS and SB reduced abdominal fat and the combination reduced abdominal fat compared to SB and RS. RS was associated with increased fermentation in the cecum. Serum PYY and GLP-1 total were increased with RS treatment. RS treatment was associated with increased cecal butyrate produced from fermentation of RS, but there was no cecal increase for dietary SB.

CONCLUSIONS

SB after its absorption into the blood appears to not affect production of PYY and GLP-1, while butyrate from fermentation in the cecum promotes increased PYY and GLP-1. Future studies with lower doses of RS and SB are warranted and the combination may be beneficial for human health.

High fat diet partially attenuates fermentation responses in rats fed resistant starch from high-amylose maize

OBJECTIVE

The effects of type 2 resistant starch from high-amylose maize (HAM-RS2) in rodents fed with low-fat diets were demonstrated in previous studies. Fish oil is also reported to reduce body fat. In the current study, the effects of high fat and fish oil on HAM-RS2 feeding in rats were investigated.

DESIGN AND METHODS

Rats were fed 0 or 27% (weight) HAM-RS2 with low (15% energy) or high fat (42% energy) diets that included 0 or 10% (energy) tuna oil to test the effect of HAM-RS2 in diet-induced obesity and effects of tuna oil. Data were analyzed as 2 × 2 × 2 factorial.

RESULTS

Rats fed HAM-RS2 had decreased cecal contents pH, increased cecal and cecal contents weight, increased cecal contents acetate, propionate, and butyrate, increased GLP-1 and PYY, and decreased abdominal fat. However, high fat partially attenuated effects of HAM-RS2, but increased GLP-1 active. Dietary tuna oil had limited effects at concentration used.

CONCLUSIONS

Results demonstrated that a high fat diet partially attenuates the response to HAM-RS2. The mechanism may center on reduced levels of cecal contents propionate and butyrate and reduced serum PYY. This study demonstrated that with consumption of high fat, HAM-RS2 produces fermentation but results in partial attenuation of effects.

Gut microbiota from twins discordant for obesity modulate metabolism in mice

The role of specific gut microbes in shaping body composition remains unclear. We transplanted fecal microbiota from adult female twin pairs discordant for obesity into germ-free mice fed low-fat mouse chow, as well as diets representing different levels of saturated fat and fruit and vegetable consumption typical of the U.S. diet. Increased total body and fat mass, as well as obesity-associated metabolic phenotypes, were transmissible with uncultured fecal communities and with their corresponding fecal bacterial culture collections. Cohousing mice harboring an obese twin's microbiota (Ob) with mice containing the lean co-twin's microbiota (Ln) prevented the development of increased body mass and obesity-associated metabolic phenotypes in Ob cage mates. Rescue correlated with invasion of specific members of Bacteroidetes from the Ln microbiota into Ob microbiota and was diet-dependent. These findings reveal transmissible, rapid, and modifiable effects of diet-by-microbiota interactions.

Resistant starch from high amylose maize (HAM-RS2) reduces body fat and increases gut bacteria in ovariectomized (OVX) rats

OBJECTIVE

Obesity after menopause is a health concern for older females. Changes in the microbiota are likely to occur with this condition. Modifying the microbiota with a prebiotic is a plausible strategy for improving the health of menopausal females.

DESIGN AND METHODS

Resistant starch type 2 from high-amylose maize (HAM-RS2) was used as a prebiotic in rats in a 2 × 2 factorial study with two levels of HAM-RS2 (0 or 29.7% of weight of diet) referred to as energy control (EC) and HAM-RS2 diets, respectively; and two levels of surgery, ovariectomized (OVX) and sham.

RESULTS

In a 6-week, postsurgery recovery period, OVX rats gained more body weight with consumption of a similar amount of food. Subsequently, consumption of HAM-RS2 versus EC diets resulted in reduced abdominal fat in both OVX and sham rats; but when normalized for disemboweled body weight (body weight minus GI tract), there was no effect of surgery, only reduction with HAM-RS2. Targeted bacterial populations were estimated that are known to ferment HAM-RS2 or metabolize the products of that initial fermentation. OVX and sham rats demonstrated increased bacterial levels with dietary HAM-RS2 for all bacteria. Additionally, culture techniques and qPCR provided similar results.

CONCLUSION

This study shows that, as expected, OVX increases adiposity. However, contrary to previous effects seen in obese mice, this did not prevent fermentation of HAM-RS2 and consequently, the fat gain associated with OVX was attenuated.

Dietary resistant starch dose-dependently reduces adiposity in obesity-prone and obesity-resistant male rats

BACKGROUND

Animal studies show that diets containing resistant starch (RS) at levels not achievable in the human diet result in lower body weight and/or adiposity in rodents. We aimed to determine whether RS dose-dependently reduces adiposity in obesity-prone (OP) and obesity-resistant (OR) rats.

METHODS

Male Sprague-Dawley rats (n=120) were fed a moderate-fat, high-energy diet for 4 wk. Rats that gained the most weight (40%) were classified as obesity-prone (OP) and obesity-resistant (OR) rats were the 40% that gained the least weight. OP and OR rats were randomly allocated to one of six groups (n=8 for each phenotype). One group was killed for baseline measurements, the other five groups were allocated to AIN-93 based diets that contained 0, 4, 8, 12 and 16% RS (as high amylose maize starch) for 4 wk. These diets were matched for total carbohydrate content. At 0, 4 and 7 wk from the start of the study insulin sensitivity was calculated by homeostasis model assessment of insulin resistance (HOMA-IR) and adiposity was determined by dual-energy X-ray absorptiometry (DXA). At 8 wk, rats were euthanized and fat pad weights, intestinal digesta short chain fatty acid (SCFA) pools and plasma gut hormone levels were determined.

RESULTS

Obesity prone rats gained less weight with 4, 12 and 16% RS compared to 0% RS, but the effect in OR animals was significant only at 16% RS. Irrespective of phenotype, diets containing ≥8% RS reduced adiposity compared to 0% RS. Energy intake decreased by 9.8 kJ/d for every 4% increase in RS. All diets containing RS increased total SCFA pools in the caecum and lowered plasma GIP concentrations compared to the 0% RS, whereas plasma GLP-1 and PYY were increased when the diet contained at least 8% RS. Insulin sensitivity was not affected by RS.

CONCLUSION

RS in amounts that could be potentially consumed by humans were effective in reducing adiposity and weight gain in OP and OR rats, due in part to a reduction in energy intake, and changes in gut hormones and large bowel carbohydrate fermentation.

Influence of diet on visceral adipose remodeling in NONcNZO10 mice with polygenic susceptibility for type 2 diabetes

Visceral adipose tissue (VAT) is a source of inflammatory cytokines that in obese subjects may contribute to low-level systemic inflammation and development of metabolic syndrome. Expansion of VAT involves adipocyte hyperplasia and hypertrophy and requires breakdown of the extracellular matrix and increased vascular outgrowth. To investigate changes of gene expression associated with VAT expansion and the role of combined genetics and diet, we implemented gene microarray analyses of VAT in NONcNZO10 (NZ10) and control SWR/J mice subjected to control chow (CD) or a diet of high protein and fish oil (HPO). NZ10 mice on CD showed increased body weight, hyperglycemia, and hyperinsulinemia at 25 weeks whereas those on HPO diet retained normal insulin levels and were normoglycemic. Two-way ANOVA revealed a significant interaction between diet and strain on blood glucose, serum insulin, and percent fat but not for body weight. Microarray heat maps revealed a remarkable combined effect of genetics and diet on genes that regulate extracellular matrix as well as angiogenic genes. Real time-PCR (RT-PCR) confirmed markedly increased expression of matrix metalloproteinases (MMPs) 2, 3, 11, and 12, vascular endothelial growth factor-A and C (VEGF-A and C), Von Willebrand Factor, and peroxisome proliferator-activated receptor-γ (PPAR-γ) selectively in the NZ10/CD group. MMP7 was significantly decreased. Protein levels of MMP2, 3, and 9 were significantly increased in the VA of NZ10 mice fed CD while those of MMP7 were downregulated. Microarrays also revealed diet-dependent two to fourfold increased expression of all four tissue inhibitor of metalloproteinases (TIMP) isoforms in NZ10 mice. Two-way ANOVA confirmed strongly interactive roles of diet and genetics on fat deposition and progression of type 2 diabetes in this polygenic mouse model.

Dietary-resistant starch and glucose metabolism

PURPOSE OF REVIEW

Recent findings in animal models suggest that resistant starch is beneficial for both body weight regulation and glycaemic control. The purpose of this review is to summarize the current evidence and recommendations in humans.

RECENT FINDINGS

When resistant starch replaces available carbohydrate in a meal, postprandial glycaemia is reduced. There are some data to suggest that resistant starch may affect glycaemia even when the available carbohydrate portion remains constant; however, there is inconsistency in the literature. Recent animal data suggest that chronic resistant starch feeding upregulates glucagon-like peptide 1 expression in the large bowel with concomitant increases in neuropeptide expression in the hypothalamus, combining to result in weight loss and improvements in glycaemic control. However, to date there is no evidence for this in humans.

SUMMARY

Resistant starch may have a role in glycaemic control in healthy individuals and those with type 2 diabetes; however, there are limited interventional trials in humans to support this. There are no data concerning resistant starch feeding in human diabetes and as such no health recommendation can be made.

Fermentable carbohydrate alters hypothalamic neuronal activity and protects against the obesogenic environment

Obesity has become a major global health problem. Recently, attention has focused on the benefits of fermentable carbohydrates on modulating metabolism. Here, we take a system approach to investigate the physiological effects of supplementation with oligofructose-enriched inulin (In). We hypothesize that supplementation with this fermentable carbohydrate will not only lead to changes in body weight and composition, but also to modulation in neuronal activation in the hypothalamus. Male C57BL/6 mice were maintained on a normal chow diet (control) or a high fat (HF) diet supplemented with either oligofructose-enriched In or corn starch (Cs) for 9 weeks. Compared to HF+Cs diet, In supplementation led to significant reduction in average daily weight gain (mean ± s.e.m.: 0.19 ± 0.01 g vs. 0.26 ± 0.02 g, P < 0.01), total body adiposity (24.9 ± 1.2% vs. 30.7 ± 1.4%, P < 0.01), and lowered liver fat content (11.7 ± 1.7% vs. 23.8 ± 3.4%, P < 0.01). Significant changes were also observed in fecal bacterial distribution, with increases in both Bifidobacteria and Lactobacillius and a significant increase in short chain fatty acids (SCFA). Using manganese-enhanced MRI (MEMRI), we observed a significant increase in neuronal activation within the arcuate nucleus (ARC) of animals that received In supplementation compared to those fed HF+Cs diet. In conclusion, we have demonstrated for the first time, in the same animal, a wide range of beneficial metabolic effects following supplementation of a HF diet with oligofructose-enriched In, as well as significant changes in hypothalamic neuronal activity.

High-amylose resistant starch increases hormones and improves structure and function of the gastrointestinal tract: a microarray study

BACKGROUND/AIMS

Type 2 resistant starch from high-amylose maize (HAM-RS2) is associated with increased fermentation, increased expression of proglucagon (gene for GLP-1) and peptide YY (PYY) genes in the large intestine, and improved health. To determine what other genes are up- or downregulated with feeding of HAM-RS2, a microarray was performed.

METHODS

Adult, male Sprague Dawley rats were fed one of the following three diets for a 4-week study period: cornstarch control (CC, 3.74 kcal/g), dietary energy density control (EC, 3.27 kcal/g), and 30% HAM-RS2 (RS, 3.27 kcal/g). Rat microarray with ∼27,000 genes and validation of 94 representative genes with multiple qPCR were used to determine gene expression in total RNA extracts of cecal cells from rats. The RS versus EC comparison tested effects of fermentation as energy density of the diet was controlled.

RESULTS

For the RS versus EC comparison, 86% of the genes were validated from the microarray and the expression indicates promotion of cell growth, proliferation, differentiation, and apoptosis. Gut hormones GLP-1 and PYY were increased.

CONCLUSIONS

Gene expression results predict improved structure and function of the GI tract. Production of gut hormones may promote healthy functions beyond the GI tract.

Wheat-derived arabinoxylan oligosaccharides with prebiotic effect increase satietogenic gut peptides and reduce metabolic endotoxemia in diet-induced obese mice

Background:

Alterations in the composition of gut microbiota —known as dysbiosis— have been proposed to contribute to the development of obesity, thereby supporting the potential interest of nutrients acting on the gut microbes to produce beneficial effect on host energetic metabolism. Non-digestible fermentable carbohydrates present in cereals may be interesting nutrients able to influence the gut microbiota composition.

Objective and design:

The aim of the present study was to test the prebiotic potency of arabinoxylan oligosaccharides (AXOS) prepared from wheat bran in a nutritional model of obesity, associated with a low-grade chronic systemic inflammation. Mice were fed either a control diet or a high fat (HF) diet, or a HF diet supplemented with AXOS during 8 weeks.

Results:

AXOS supplementation induced caecal and colon enlargement associated with an important bifidogenic effect. It increased the level of circulating satietogenic peptides produced by the colon (peptide YY and glucagon-like peptide-1), and coherently counteracted HF-induced body weight gain and fat mass development. HF-induced hyperinsulinemia and the Homeostasis Model Assessment of insulin resistance were decreased upon AXOS feeding. In addition, AXOS reduced HF-induced metabolic endotoxemia, macrophage infiltration (mRNA of F4/80) in the adipose tissue and interleukin 6 (IL6) in the plasma. The tight junction proteins (zonula occludens 1 and claudin 3) altered upon HF feeding were upregulated by AXOS treatment suggesting that the lower inflammatory tone was associated with the improvement of gut barrier function.

Conclusion:

Together, these findings suggest that specific non-digestible carbohydrates produced from cereals such as AXOS constitute a promising prebiotic nutrient in the control of obesity and related metabolic disorders.

Tolerance, fermentation, and cytokine expression in healthy aged male C57BL/6J mice fed resistant starch

Health benefits of resistant starch (RS), a dietary fermentable fiber, have been well documented in young, but not in old populations. As the essential step of more comprehensive evaluations of RS on healthy aging, we examined the effects of dietary RS on tolerance, colonic fermentation, and cytokine expression in aged mice. Healthy older (18-20 months) C57BL/6J male mice were fed control, 18% RS, or 36% RS diets for 10 weeks. Body weight gain, body composition, and fat pad weights did not differ among the three groups after 10 weeks, indicating good tolerance of the RS diet. Fermentation indicators (cecum weights, and cecal proglucagon and PYY mRNA expression) were enhanced in an RS dose-dependent manner (p<0.01). Serum concentrations of soluble cytokine receptors (sTNF-Rb, sIL-4R, sIL-2Rα, sVEGFR1, and sRAGE) and TNFα expression (gene and protein) in visceral fat did not differ significantly among groups. Adiponectin protein concentrations, but not gene expression, were greater in epididymal fat of the 36% RS versus control groups (p<0.05). As a conclusion in aged mice, dietary RS is well tolerated, fermented in the colon, and stimulates colonic expression of proglucagon and PYY mRNA, and adiponectin protein in visceral fat.

The interaction of short-chain fatty acids with adipose tissue: relevance for prevention of type 2 diabetes

Short chain fatty acids (SCFA) are the main bacterial metabolites of colonic fermentation processes. The physiological relevance of the SCFA for the host outside the gastrointestinal tract is getting increased attention. In this review we will focus on the effect of SCFA on inflammation processes in the host in relation to insulin resistance. Obesity has been associated with a pro-inflammatory state of the adipose tissue that is associated with whole body insulin resistance leading to type 2 diabetes. Recently, two G protein-coupled receptors (GPCR) for SCFA, GPCR 41 and GPCR43, were described that are mainly expressed by immune cells but also by adipose tissue. Propionate can induce the satiety hormone leptin and reduce expression of inflammatory cytokines and chemokines indicating that SCFA have anti-inflammatory effects in human adipose tissue. In addition, in human nutritional experiments we observed that whole grain products could counteract a glucose-induced tumour necrosis factor α and interleukin-6 increase which was associated with increased plasma butyrate concentrations. This suggests that dietary fibre can produce a SCFA profile that could have anti-inflammatory effects in the body. The physiological relevance of these observations especially in relation to obesity-associated inflammation and insulin resistance is discussed.

Resistant starch and exercise independently attenuate weight regain on a high fat diet in a rat model of obesity

BACKGROUND

Long-term weight reduction remains elusive for many obese individuals. Resistant starch (RS) and exercise may be useful for weight maintenance. The effects of RS, with or without exercise, on weight regain was examined during relapse to obesity on a high carbohydrate, high fat (HC/HF) diet.

METHODS

Obesity-prone rats were fed ad libitum for 16 weeks then weight reduced on a low fat diet to induce a 17% body weight loss (weight reduced rats). Weight reduced rats were maintained on an energy-restricted low fat diet for 18 weeks, with or without a daily bout of treadmill exercise. Rats were then allowed free access to HC/HF diet containing low (0.3%) or high (5.9%) levels of RS. Weight regain, energy balance, body composition, adipocyte cellularity, and fuel utilization were monitored as rats relapsed to obesity and surpassed their original, obese weight.

RESULTS

Both RS and exercise independently attenuated weight regain by reducing the energy gap between the drive to eat and suppressed energy requirements. Exercise attenuated the deposition of lean mass during relapse, whereas its combination with RS sustained lean mass accrual as body weight returned. Early in relapse, RS lowered insulin levels and reduced the deposition of fat in subcutaneous adipose tissue. Exercise cessation at five weeks of relapse led to increased weight gain, body fat, subcutaneous adipocytes, and decreased lean mass; all detrimental consequences to overall metabolic health.

CONCLUSIONS

These data are the first to show the complimentary effects of dietary RS and regular exercise in countering the metabolic drive to regain weight following weight loss and suggest that exercise cessation, in the context of relapse on a HC/HF diet, may have dire metabolic consequences.

Dietary-resistant starch improves maternal glycemic control in Goto-Kakizaki rat

SCOPE

Dietary prebiotics show potential in anti-diabetes. Dietary resistant starch (RS) has a favorable impact on gut hormone profiles, including glucagon-like peptide-1 (GLP-1) consistently released, a potent anti-diabetic incretin. Also RS reduced body fat and improved glucose tolerance in rats and mice. In the current project, we hypothesize that dietary-resistant starch can improve insulin sensitivity and pancreatic β cell mass in a type 2 diabetic rat model. Altered gut fermentation and microbiota are the initial mechanisms, and enhancement in serum GLP-1 is the secondary mechanism.

METHODS AND RESULTS

In this study, GK rats were fed an RS diet with 30% RS and an energy control diet. After 10 wk, these rats were mated and went through pregnancy and lactation. At the end of the study, pancreatic β cell mass, insulin sensitivity, pancreatic insulin content, total GLP-1 levels, cecal short-chain fatty acid concentrations and butyrate producing bacteria in cecal contents were greatly improved by RS feeding. The offspring of RS-fed dams showed improved fasting glucose levels and normal growth curves.

CONCLUSION

Dietary RS is potentially of great therapeutic importance in the treatment of diabetes and improvement in outcomes of pregnancy complicated by diabetes.

Resistant starch, fermented resistant starch, and short-chain fatty acids reduce intestinal fat deposition in Caenorhabditis elegans

Obesity is a growing global public health dilemma. The objective of this project is to develop and validate a screening mechanism for bioactive compounds that may reduce body fat and promote health. Resistant starch (RS) reduces body fat in rodents. Amylose starch that has a high content of RS, endogenous compounds obtained from the ceca of amylose starch fed mice (fermented RS), and individual short-chain fatty acids (SCFA) were tested. The Caenorhabditis elegans model and Nile red staining were selected to determine the intestinal fat deposition response to bioactive components. The fluorescence intensity of Nile red was reduced to 76.5% (amylose starch), 78.8% (fermented RS), 63.6% (butyrate), or 28-80% (SCFAs) of controls, respectively (P < 0.001). The reduced intestinal fat deposition suggests reduced food intake or increased energy expenditure. C. elegans is a practical animal model to screen for bioactive compounds that may prevent or treat obesity.